This invention provides a new self regulating circuit between the local voice telephone plant and the input, output or interface between links of long distance built up voice trunks. Voice signals applied to long distance trunks may originate in any one of many different local switching areas having different mean volumes as well as individual circuit and talker variations. The voice signal generated in telephone sets and delivered over local loops to the input or delivered from long distance trunk circuits over local loops to the input or delivered from long distance trunks can be divided into two parts occupying different frequency bands; first, the amplitude of the informational voice signal occupies a frequency band from just above direct current to include all frequencies to just below about 100 Hertz at decreasing amplitudes with respect to frequency. Second, the information signal is usually considered to occupy a band from about 0.2 to 3.4 kiloHertz with about the same average power in each incremental band. These signals are generated in individual transducers in response to sound pressures from a universe of talkers. The electrical signal is usually considered to be a convolution of vocal cord frequencies, glottal and voice box impulses. That is, the signal is considered to be of the form f(A)t .times. f(B)t. The frequencies contained in the individual terms are non-overlapping or nearly so, and can be separated by demodulation and frequency selection. The relative amplitudes of the components may be changed by equalization or amplification and attenuation of the individual components selected by filtering. The desired signal output can be attained from the telephone set by rearranging the relative amplitudes and recombining the components in a product modulator to obtain increased signal amplitude in the original form or as desired. The long distance transmission circuits were designed to give satisfactory performance when the signal applied has a specific means with a normal talker volume standard deviation produced by a talker sound pressures from large local office areas. When the signal originates in a small local office area, the mean volume changes from office to office. The variation between offices added to the variability of the talker sound pressure that might be applied to a transmitting transducer and in turn to a long distance trunk is increased above the variability of a individual talker from a particular large office area. The number of users rating the transmitting circuits "good" for trunks with booster station designed for a higher mean volume will be reduced with the increased standard deviation or variation of the applied talker signal. If the standard deviation of the voice signal is reduced, a greater proportion of the users will rate the circuit "good".
The object of this invention is to disclose a means of modifying and reducing the signal variation applied to long distance trunks from any originating local area. Preferred signal volume is delivered to the listener with a minimum amplitude change due to individual talkers at the trunk input. Variations in the net loss can be removed by providing a receiving regulator.